Ship project history:Designed by Fiat-San Giorgio and Eng Lt Cdr Cesare Laurenti,
they were the first Italian submarines to have diesel motors. These required
long trials and time for adjustment. They were very good boats when submerged,
with good manoeuvrability and stability.

Modernizations: None.

Naval service:Jalea sunk in the Gulf of Trieste by an Austrian mine 17/8/1915.
Medusa sunk 10/6/1915 off Porto di Piave Vecchia (N Adriatic), torpedoed by
the German submarine UB15, disguised as the Austrian U11. Zoea
beached on 26 November 1917, by storm, at Rimini; salvaged by tug Ciclope
and some torpedo-boats, and towed to Venice on 1 December for repairs. That
month Venice N Yd began work to convert Argo into an assault submarine
for forcing the Austrian main base of Pola, with the aid of frogmen for breaking
the harbour barrages.